gistfile1.txt

package mytest

import (
	"errors"
	"fmt"
	"net/http"
	"io"
	"io/ioutil"
	"testing"
	"context"
	"net/http/httptest"
	"github.com/docker/docker/client"
	"github.com/docker/docker/api/types"
)

func mockResponse(target string) (string, error) {
	supportedEndpoints := []string{
	 	"/containers/json",
	}

	// Is endpoint supported?
	supported := false
	for _, endpoint := range supportedEndpoints {
		if endpoint == target {
			supported = true
		}
	}

	if !supported {
		return "", errors.New("Not supported endpoint")
	}

	var mockData string

	switch target {
	case "/containers/json":
		dat, err := ioutil.ReadFile("/tmp/list_containers")

		if err != nil {
			return "", err
		}

		mockData = string(dat)
	}

	return mockData, nil
}

func NewMockDockerClient(mockServerURL string) (*client.Client, error) {
	httpClient := &http.Client{
		Transport: new(http.Transport),
	}

	cli, err := client.NewClient(mockServerURL, "v1.24", httpClient, nil)

	if err != nil {
		return nil, err
	}

	return cli, nil
}

func NewMockDockerServer(responseFunc func(w http.ResponseWriter, r *http.Request), endpoint string) (*httptest.Server, error) {
	ts := httptest.NewServer(http.HandlerFunc(
		responseFunc,
	))

	return ts, nil
}

func TestContainersList(t *testing.T) {
	responseBody, err := mockResponse("/containers/json")

	if err != nil {
		t.Error(err)		
	}

	ts, err := NewMockDockerServer(
		func(w http.ResponseWriter, r *http.Request) {
			w.Header().Set("content-Type", "application/json")
			io.WriteString(w, responseBody)
			return
		}, "/containers/json")

	defer ts.Close()

	if err != nil {
		t.Errorf("Fail to create Docker mock server")
	}

	cli, err := NewMockDockerClient(ts.URL)

	if err != nil {
		t.Error(err)
	}

	res, err := cli.ContainerList(context.Background(), types.ContainerListOptions{})

	if err != nil {
		t.Error(err)		
	}

	fmt.Println(res)
}